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Unformatted text preview: Effect of creep feed supplementation and season on intake, microbial protein synthesis and efficiency, ruminal fermentation, digestion, and performance in nursing calves grazing native range in southeastern North Dakota 1 J. J. Reed, A. L. Gelvin, G. P. Lardy, M. L. Bauer, and J. S. Caton 2 Department of Animal and Range Sciences, North Dakota State University, Fargo 58105 ABSTRACT: Nine ruminally and duodenally cannu- lated (172 23 kg of initial BW; Exp. 1) and 16 intact (153 28 kg of initial BW; Exp. 2) crossbred nursing steer calves were used to evaluate the effects of creep feed supplementation and advancing season on intake, digestion, microbial efficiency, ruminal fermentation, and performance while grazing native rangeland. Treatments in both experiments were no supplement or supplement fed at 0.45% of BW (DM basis) daily. Supplement consisted of 55% wheat middlings, 38.67% soyhulls, 5% molasses, and 1.33% limestone. Three 15- d collection periods occurred in June, July, and August. In Exp. 1, ruminal evacuations were performed and masticate samples were collected for diet quality analy- sis on d 1. Duodenal and fecal samples were collected from cannulated calves on d 7 to 12 at 0, 4, 8, and 12 h after supplementation. Ruminal fluid was drawn on d 9 and used as the inoculate for in vitro digestibility. On d 11, ruminal fluid was collected, and the pH was recorded at 1, 1, 2, 4, 8, 12, and 24 h postsupplementa- tion. In Exp. 1 and 2, milk intake was estimated using weigh-suckle-weigh on d 15. Steers in Exp. 2 were fitted with fecal bags on d 6 to 11 to estimate forage intake. Key words: calf, creep feed, digestibility, forage, intake, supplementation 2006 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2006. 84:411423 INTRODUCTION Creep feeding has traditionally been used to increase weaning weights, reduce grazing pressure, and improve feed intake at weaning. Weaning weight is an im- portant factor affecting profitability for producers who sell their calves at weaning. Creep feeding studies have consistently shown increases in weaning weight in creep-fed calves (Faulkner et al., 1994; Lardy et al., 1 Partially supported by regional research funds NC-189. Gratitude is expressed to personnel of the NDSU Beef Unit, the Albert Ekre Grasslands Preserve, and the NDSU Nutrition Laboratory. 2 Corresponding author: email@example.com Received March 22, 2005. Accepted October 4, 2005. 411 In Exp. 1, supplementation had no effect ( P = 0.22 to 0.99) on grazed diet or milk composition. Apparent total tract OM disappearance increased ( P = 0.03), and ap- parent total tract N disappearance tended ( P = 0.11) to increase in supplemented calves. Microbial efficiency was not affected ( P = 0.50) by supplementation. There were no differences in ruminal pH ( P = 0.40) or total VFA concentration ( P = 0.21) between treatments, whereas ruminal NH 3 concentration increased ( P = 0.03) in supplemented compared with control calves. In0....
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